Biomechanical Assessment of Mobile-Bearing Total Knee Endoprostheses Using Musculoskeletal Simulation

The purpose of this computational study was to analyze the effects of different mobile-bearing (MB) total knee replacement (TKR) designs on knee joint biomechanics. A validated musculoskeletal model of the lower right extremity implanted with a cruciate-retaining fixed-bearing TKR undergoing a squat motion was adapted for three different MB TKR design variants: (I) a commercially available TKR design allowing for tibial insert rotation about the tibial tray with end stops to limit the range of rotation, (II) the same design without end stops, and (III) a multidirectional design with an additional translational degree-of-freedom (DoF) and end stops. When modeling the MB interface, two modeling strategies of different joint topologies were deployed: (1) a six DoF joint as a baseline and (2) a combined revolute-prismatic joint (two DoF joint) with end stops in both DoF. Altered knee joint kinematics for the three MB design variants were observed. The commercially available TKR design variant I yielded a deviation in internal-external rotation of the tibial insert relative to the tray up to 5° during knee flexion. Compared to the multidirectional design variant III, the other two variants revealed less femoral anterior-posterior translation by as much as 5 mm. Concerning the modeling strategies, the two DoF joint showed less computation time by 68%, 80%, and 82% for design variants I, II, and III, respectively. However, only slight differences in the knee joint kinematics of the two modeling strategies were recorded. In conclusion, knee joint biomechanics during a squat motion differed for each of the simulated MB design variants. Specific implant design elements, such as the presence of end stops, can impact the postoperative range of knee motion with regard to modeling strategy, and the two DoF joint option tested accurately replicated the results for the simulated designs with a considerably lower computation time than the six DoF joint. The proposed musculoskeletal multibody simulation framework is capable of virtually characterizing the knee joint dynamics for different TKR designs.

The Cadaveric Studies and the Definition of the Antero-Lateral Ligament of the Knee: From the Anatomical Features to the Patient-Specific Reconstruction Surgical Techniques

Cadaver studies represented a milestone in surgical orthopaedic research, and still today they play a crucial role in the achievement of new knowledge about joint disease behaviour and treatment. In this review, an overview of the cadaver studies available in the literature about the anatomy, role, and treatment of the antero-lateral ligament (ALL) of the knee was performed. The aim of the review was to describe and gain more insight into the part of in vitro study in understanding knee joint anatomy and biomechanics, and in developing surgical reconstruction techniques. The findings of the review showed that cadaver studies had, and will continue to have, a key role in the research of knee joint biomechanics and surgical reconstruction. Moreover, they represent a powerful tool to develop and test new devices which could be useful in clinical and surgical practice.

Anatomically-based skeleton kinetics and pose estimation in freely-moving rodents

Forming a complete picture of the relationship between neural activity and body kinetics requires quantification of skeletal joint biomechanics during behavior. However, without detailed knowledge of the underlying skeletal motion, inferring joint kinetics from surface tracking approaches is difficult, especially for animals where the relationship between surface anatomy and skeleton changes during motion. Here we developed a videography-based method enabling detailed three-dimensional kinetic quantification of an anatomically defined skeleton in untethered freely-behaving animals. This skeleton-based model has been constrained by anatomical principles and joint motion limits and provided skeletal pose estimates for a range of rodent sizes, even when limbs were occluded. Model-inferred joint kinetics for both gait and gap-crossing behaviors were verified by direct measurement of limb placement, showing that complex decision making behaviors can be accurately reconstructed at the level of skeletal kinetics using our anatomically constrained model.

Congenital Distal Tibiofibular Synostosis - A Case Report

Congenital tibiofibular synostosis is the fusion of tibia and fibula since birth. So far there are many reports of congenital proximal tibio fibular synostosis in English literature, but congenital distal tibio fibular synostosis is very rarely described. Imaging studies by means of X rays, CT and MRI are required to rule out osteochondromas arising from distal tibia, fibula and other conditions. If the patient is symptomatic by means of deformity surgical intervention in the form of corrective osteotomy may be considered to prevent alternation of joint biomechanics. We report a rare case of congenital distal tibiofibular synostosis in a 21 year old female presented with complaints of deformity and pain on and off in left lower leg since childhood. Key words: Congenital; Synostosis; Deformity; Osteochondroma.

728 Histomorphology Of the Subregions of The Scapholunate Interosseous Ligament and Its Enthesis

Introduction The scapholunate interosseous ligament (SLIL) is commonly ruptured following a fall onto the outstretched hand. This ligament has three subregions: dorsal, proximal, and volar. The SLIL enthesis, a specialised region where this ligament attaches to the scaphoid and lunate, has not previously been studied despite its important mechanical function in the wrist joint biomechanics. This study therefore aims to compare the histomorphological differences between the three SLIL subregions, including at their entheses, to inform subregion prioritisation during surgical reconstruction. Method Twelve fresh-frozen human cadaveric wrists were dissected and the gross dimensions of the SLIL subregions measured. Subregions were histologically processed for analysis, including quantification of enthesis calcified fibrocartilage (CF) area. Results From the gross measurements, the dorsal subregion was the thickest (dorsal=3.04 ± 0.26mm, volar=1.69 ± 0.08mm, proximal=1.51 ± 0.06mm). The dorsal and volar subregions had fibrocartilaginous entheses while the proximal subregion was attached to articular cartilage. The dorsal subregion had significantly more CF than the volar subregion. Conclusions The dorsal subregion is the thickest and has the greatest CF area, which is consistent with the greatest biomechanical force subjected to this subregion. These results confirm that the dorsal subregion is the strongest subregion, suggesting important implications in the study of graft incorporation during SLIL reconstruction.

METHODS OF INTERPRETATION OF DATA FROM ISOKINETIC TESTS AND MRI STUDIES DURING REHABILITATION OF PATIENTS AFTER RECONSTRUCTIVE SHOULDER JOINT SURGERY

The research results in the field of computer visualization of the shoulder joint biomechanics are presented. The possibilities of using biomechanical robotic mechanotherapy on the CON-TREX complex in the rehabilitation treatment of patients after arthroscopic shoulder surgery are shown. The possibilities of additional visualization of magnetic resonance imaging (MRI) data using spectral decomposition methods (Shearlet transform and contrasting with color coding) are studied. Experiments with the use of the proposed diagnostic technique are described. The relationship between the MRI data and CON-TREX protocols in planning and implementation of the rehabilitation procedures is demonstrated. The technique which allows to improve the quality and availability of the MRI data in the study of the shoulder joint biomechanics during restorative treatment is described.